“The attack on Elena Urlaeva shows how far the government is willing to go to cover up evidence of forced labour and to retaliate against those who expose it.”

She had photographed a group of doctors from the town of Chinaz whom local officials had ordered to work in the fields. The state obliges millions of citizens to work for periods in the cotton fields for minimal pay each year, earning it large revenues.

Uzbek officials could not be immediately reached for comment.

International human rights bodies say there are thousands of political and religious prisoners in Uzbekistan, a mainly Muslim Central Asian nation of 30 million. Torture and arbitrary extensions of imprisonment are rife in local jails, they say.

Human rights issues are likely to loom large during United Nations Secretary-General Ban Ki-moon’s visit to Uzbekistan expected next week.

President Islam Karimov, in power since 1989, justifies his tough rule on the grounds of a need to prevent the spread of radical Islam.

Western governments criticise violations of human rights in Uzbekistan, but also value it as a key ally in the volatile region which borders Afghanistan. NATO has its Central Asia office in Tashkent.

“Uzbekistan’s international partners, including the U.S. government and the EU, should make clear the specific policy consequences that will follow if Tashkent does not take immediate, concrete steps to allow rights activists to carry out their work,” HRW said.

It said such consequences should include visa bans and asset freezes against government officials responsible for grave human rights violations.